ES2701819T3 - Method to convert a high-boiling hydrocarbon feedstock into lower-boiling hydrocarbon products - Google Patents

Abstract

A process for converting a high-boiling hydrocarbon feedstock to lower-boiling hydrocarbon products, said boiling-point hydrocarbon products being suitable as feedstock for petrochemical processes, said conversion process comprising the following steps of: feeding a first heavy hydrocarbon material to a cascade of hydrocracking units, the cascade of hydrocracking units comprising at least two hydrocracking units, cracking said raw material in a hydrocracking unit, separating said cracked raw material into an overhead stream comprising a fraction of low boiling hydrocarbons and a lower stream comprising a heavy hydrocarbon fraction feeding said lower stream of such a hydrocracking unit as a raw material for a subsequent hydrocracking unit in said cascade of hydrocracking units, being the process conditions in each of the hydrocracking units different from each other, in which the temperature from the first to the subsequent hydrocracking units increases, and processing the fractions of hydrocarbons of lower boiling point of each of the units of hydrocracking as a raw material for a BTX and LPG production unit, said BTX and LPG production unit being a hydrocracking unit, the process conditions prevailing in said hydrocracking unit being different from the process conditions prevailing in a any of the hydrocracking units in the cascade of hydrocracking units, each hydrocracking unit being operated in said cascade of hydrocracking units under liquid phase hydrocracking conditions, and said hydrocracking unit being operated as said BTX production unit and LPG under hydrocracking conditions in gas phase.

Description

DESCRIPTION

Method to convert a high-boiling hydrocarbon feedstock into lower-boiling hydrocarbon products

The present invention relates to a process for converting a high-boiling hydrocarbon feedstock into lower-boiling hydrocarbon products. In more detail, the present invention relates to a process for converting hydrocarbons, especially hydrocarbons from refinery operations, such as, for example, an atmospheric distillation unit or a fluid catalytic cracking unit (FCC), into hydrocracked hydrocarbons of lower boiling point which have a lower boiling point than naphthalene and lower boiling point.

U.S. Patent No. 4,137,147 relates to a process for making ethylene and propylene from a filler having a distillation point less than about 360 ° C and containing at least normal paraffins and isoparaffins having at least 4. carbon atoms per molecule, in which: the charge is subjected to a hydrogenolysis reaction in a hydrogenolysis zone, in the presence of a catalyst, (b) the effluents from the hydrogenolysis reaction are fed to a separation zone from the which are discharged (i) from the top, methane and possibly hydrogen, (ii) a fraction consisting essentially of hydrocarbons with 2 and 3 carbon atoms per molecule, and (iii) from the bottom, a fraction consisting essentially of in hydrocarbons with at least 4 carbon atoms per molecule, (c) only the fraction consisting essentially of hydrocarbons with 2 and 3 carbon atoms per molecule is fed to a cracked area or steam, in the presence of steam, to transform at least a part of the hydrocarbons with 2 and 3 carbon atoms per molecule into monoolefinic hydrocarbons; The fraction consisting essentially of hydrocarbons with at least 4 carbon atoms per molecule, obtained from the lower part of the separation zone, is supplied to a second hydrogenolysis zone, in which the effluent is treated in the presence of a catalyst. of the second hydrogenolysis zone is supplied to a separation zone to discharge, on the other hand, hydrocarbons with at least 4 carbon atoms per molecule that are at least partially recirculated to the second hydrogenolysis zone, and, on the other hand, a fraction consisting essentially of a mixture of hydrogen, methane and saturated hydrocarbons with 2 and 3 carbon atoms per molecule; a stream of hydrogen and a stream of methane are separated from the mixture and to the steam cracking zone the hydrocarbons are fed from the mixture with 2 and 3 carbon atoms, together with the fraction consisting essentially of hydrocarbons with 2 and 3 atoms carbon per molecule as recovered from the separation zone after the first hydrogenolysis zone. Therefore, at the outlet of the steam cracking zone, in addition to a stream of methane and hydrogen and a stream of paraffinic hydrocarbons with 2 and 3 carbon atoms per molecule, olefins with 2 and 3 carbon atoms per molecule are obtained. and products with at least 4 carbon atoms per molecule.

U.S. Patent No. 3,317,419 refers to a process for hydrorefining a hydrocarbon charge reserve comprising hydrocarbons that is boiling above the boiling range of gasoline, a process comprising the steps of: (a) submitting to hydrocracking and hydrorefining said charge reserve in admixture with hydrogen in a first reaction zone containing a hydrorefining catalytic composite material; (b) separating the effluent of normally liquid product from said first reaction zone into a first light fraction and a heavier fraction; (c) combining at least a portion of said first light fraction with a mixture of hydrocarbons and reacting the resulting mixture with hydrogen at a temperature within said range in a second reaction zone containing a hydrorefining catalytic composite and maintained in less stringent conversion conditions than said first zone; (d) separating the effluent of normally liquid product from said second reaction zone into a second light fraction and a second, hydrorefined heavy fraction; (e) combining at least a portion of said second light fraction with a mixture of hydrocarbons, reacting the resulting mixture with hydrogen in a third reaction zone containing a hydrorefining catalytic composite and maintained under conditions to effect a hydrorefining hydrogenated said mixture within a minimum hydrocracking; and, (f) separating the product effluent from said third reaction zone in a normally gaseous phase and a third heavy hydrorefined fraction.

GB 1,161,725 relates to a process for selectively producing hydrocarbons in the boiling range of gasoline by hydrocracking which comprises contacting under hydrocracking conditions a hydrocarbon feed of heavy petroleum with an amorphous hydrocracking catalyst and a catalyst. of hydrocracking of zeolite base, said contacting being carried out in a series of catalyst beds, wherein said amorphous base catalyst is separated from said zeolite base catalyst, recovering a normally liquid effluent from the last catalyst bed, separating a fraction in the boiling range of the gasoline of said liquid effluent, and recirculating at least a portion of the liquid effluent which is boiling above the range of gasoline to come into contact with the bed of amorphous base hydrocracking catalyst. The conditions in the first phase of hydrocracking are maintained at a temperature in the range of between 550 F and 750 F and a total pressure in the range of between 1000 psig and 3000 psig, while the conditions in the second phase of hydrocracking are similar , that is, maintained at a temperature between 550 F and 750 F, and a total pressure between 1000 psig and 2000 psig.

U.S. Patent No. 3,360,456 refers to a process for the hydrocracking of hydrocarbons in two phases to produce gasoline with a reduced consumption of hydrogen, in which the temperature conditions in the first phase of hydrocracking are higher than the temperature conditions. in the second phase of hydrocracking. GB 1,020,595 relates to a process for the production of naphthalene and benzene which comprises passing a raw material, containing alkyl-substituted aromatic hydrocarbons boiling in the range 200-600 F and comprising both alkylbenzenes and alkylnaphthalenes , to a first hydrocracker at a temperature of from 800 to 1100 F, a pressure of from 150 to 1000 psig, or in the absence of a catalyst at a temperature of from 1000 to 1100 F, a pressure of from 150 to 1000 psig, the cracked product to hydrocracking in a second hydrocracker either in the presence of a catalyst at a temperature of from 900 to 1200 F, a pressure of from 150 to 1000 psig or else in the absence of a catalyst at a temperature of from 1100 to 1800 F and a pressure of from 50 to 2500 psig.

U.S. Patent No. 3,660,270 refers to a process for producing gasoline comprising hydrocracking a petroleum distillate in a first conversion zone, separating the effluent from the first conversion zone into a light naphtha fraction, a second fraction that it has an initial boiling point of between 180 and 280 F, and a final boiling point of between about 500 'and 600 F., and a third heavy fraction, hydrocracking and dehydrogenating the second fraction in a second conversion zone in the presence of a catalyst and recovering at least one naphtha product from the second conversion zone.

U.S. Patent Application No. 2007/112237 refers to a method of preparing aromatic hydrocarbons and liquefied petroleum gas (LPG) from a mixture of hydrocarbons, comprising the following steps of: (a) introducing a mixture of hydrocarbon feedstocks and hydrogen in at least one reaction zone; (b) converting the mixture of hydrocarbon feedstocks in the presence of a catalyst into (i) a non-aromatic hydrocarbon compound that is rich in LPG through hydrocracking and in (ii) an aromatic hydrocarbon compound that is rich in benzene, toluene and xylene (BTX) through dealkylation / transalkylation within the reaction zone; and (c) recovering the LPG and the aromatic hydrocarbon compound, respectively from the reaction products of step (b) through gas-liquid separation and distillation.

WO2008 / 043066 relates to a process for producing one or more middle distillate fuels, which includes (a) dehydrogenating / flavoring a stream of paraffinic naphtha to give an olefin-containing composition and aromatic hydrocarbons (b) subjecting the olefins and the aromatic components to aromatic alkylation, and (c) separating the alkylaromatic compounds from the middle distillate range.

U.S. Patent No. 5,603,824 refers to an integrated hydroprocessing method, in which hydrocracking, dewaxing and desulfurization all take place in a single two-bed vertical reactor, in which a distillate is divided into heavy fractions. and light, the heavy fraction being subjected to hydrocracking and partially desulphurising in the upper reactor bed, and the effluent from the upper bed is then combined with the light fraction and introduced by cascade into the lower reactor bed, where the dewaxing takes place. a pour point reduction and an additional desulfurization.

US Patent Application No. 2003/221990 relates to a process for the production of light products, such as gas and naphtha, by processing kerosene in a second phase of a multi-phase hydrocracker, in which kerosene, diesel and naphtha from other sources are included in the recirculation, and the subsequent hydroprocessing phases are maintained at lower pressures than the initial hydroprocessing phase.

Conventionally, the crude is processed, by means of distillation, to give several cuts such as naphtha, gas oils and waste. Each of these cuts has several potential uses. such as to produce transportation fuels, such as gasoline, diesel and kerosene or as feeds for some petrochemicals and other processing units.

Light crude cuts, such as naphthas and some gas oils, can be used to produce light olefins and single ring aromatics by processes, such as steam cracking, in which the hydrocarbon feed stream is evaporated and diluted with steam and then exposed to a very high temperature (from 800 ° C to 860 ° C) in furnace (reactor) tubes of short residence time (<1 second). In a process of this type, the hydrocarbon molecules in the feed are transformed into shorter (on average) molecules and molecules with lower hydrogen to carbon ratios (such as olefins) compared to the feed molecules. This process also generates hydrogen as a useful by-product and significant quantities of co-products of lower value, such as methane and C9 + aromatics and condensed aromatic species (containing two or more aromatic rings sharing edges).

Normally, streams rich in heavier (or higher boiling) aromatic compounds, such as waste, are further processed in a crude refinery to maximize the yields of lighter (distillable) crude products. This processing can be carried out by processes such as hydrocracking (whereby the hydrocracker feed is exposed to a suitable catalyst in conditions that result in some fraction of the feed molecules breaking into shorter hydrocarbon molecules with the simultaneous addition of hydrogen). The hydrocracking of heavy refinery current is normally carried out at high pressures and temperatures and therefore has a high capital cost. One aspect of a combination of this type of crude distillation and steam cracking of the lighter distillation cuts are the capital and other costs associated with the fractional distillation of crude oil. Heavier crude cuts (ie those that boil beyond ~ 350oC) are relatively rich in substituted aromatic species and especially substituted condensed aromatic species (containing two or more aromatic rings sharing edges) and under cracking conditions. steam these materials produce substantial amounts of heavy byproducts, such as C9 + aromatics and condensed aromatics. Therefore, a consequence of the conventional combination of crude distillation and steam cracking is that a substantial fraction of the crude, for example, 50% by weight, is not processed by means of the steam cracker, since it is considered that the Cracking performance of valuable products from heavier cuts is not high enough.

Another aspect of conventional hydrocracking of heavy refinery streams, such as waste, is that it is normally carried out under compromise conditions, which are chosen to achieve the desired overall conversion. As the feed streams contain a mixture of species with a range of ease of cracking, this results in that some fraction of the distillable products formed by hydrocracking of hydrocracked species relatively easily becomes additionally the conditions necessary to hydrocrack more species. difficult to hydrocrack. This increases hydrogen consumption and the heat management difficulties associated with the process. This also increases the performance of light molecules, such as methane, at the expense of more valuable species.

US Patent Applications Nos. 2012/0125813, US 2012/0125812 and US 2012/0125811 relate to a process for cracking a heavy hydrocarbon feed comprising a vaporization step, a distillation step, a coking step, a hydroprocessing stage and a steam cracking stage. For example, US Patent Application No. 2012/0125813 relates to a process for steam cracking a heavy hydrocarbon feed to produce ethylene, propylene, C4 olefins, pyrolysis gasoline and other products, in which steam cracking of hydrocarbons, ie a mixture of a hydrocarbon feed such as ethane, propane, naphtha, gas oil or other hydrocarbon fractions, is a non-catalytic petrochemical process that is widely used to produce olefins, such as ethylene, propylene, butenes, butadiene, and aromatic compounds, such as benzene, toluene and xylenes.

U.S. Patent Application No. 2009/0050523 relates to the formation of olefins by thermal cracking in a pyrolysis furnace of liquid complete crude and / or condensate derived from natural gas in a manner that is integrated with a hydrocracking operation.

U.S. Patent Application No. 2008/0093261 relates to the formation of olefins by thermal cracking of hydrocarbons in a pyrolysis furnace of liquid and / or natural gas-derived crude oil in a manner that is integrated with a crude oil refinery. .

An object of the present invention is to provide a method for converting a high-boiling hydrocarbon feedstock to lower-boiling hydrocarbon products.

Another object of the present invention is to provide a method for producing low boiling hydrocarbon products that can be used as a raw material for further chemical processing.

Another object of the present invention is to provide a method for converting a high-boiling hydrocarbon feedstock into a fraction of BTX aromatics and an LPG fraction, wherein said LPG fraction can be used to produce light olefins.

Another object of the present invention is to provide a method for converting a high-boiling hydrocarbon feedstock into high-value products, in which the production of low-value products, such as methane and C9 + aromatics, is minimized.

The present invention relates to a process for converting a high-boiling hydrocarbon feedstock into lower-boiling hydrocarbon products, said boiling-point hydrocarbon products being suitable as feedstock for petrochemical processes, said conversion process comprising The following stages of:

feeding a heavy hydrocarbon first material to a cascade of hydrocracking units, the cascade of hydrocracking units comprising at least two hydrocracking units,

cracking said raw material in a hydrocracking unit,

separating said cracked raw material into an upper stream comprising a fraction of low boiling hydrocarbons and a lower stream comprising a heavy hydrocarbon fraction feeding said lower stream of a hydrocracking unit of this type as a raw material for a unit of subsequent hydrocracking in said cascade of hydrocracking units, the process conditions in each hydrocracking unit being different from each other, in which the temperature from the first to the subsequent hydrocracking units increases, and

process the lower boiling hydrocarbon fractions of each hydrocracking unit as raw material for a BTX and LPG production unit, said BTX and LPG production unit being a hydrocracking unit, with the process conditions prevailing in said hydrocracking unit different from the process conditions prevailing in any one of the hydrocracking units in the cascade of hydrocracking units, each hydrocracking unit being operated in said cascade of hydrocracking units under liquid phase hydrocracking conditions, and said hydrocracking unit being operated as said production unit of BTX and LPG under hydrocracking conditions in the gas phase. According to the present process it is preferred that the lower boiling hydrocarbon fractions of all the hydrocracking units in said cascade of hydrocracking units are hydrocarbons having a boiling point lower than that of naphthalene.

According to the present invention a hydrocarbon raw material, for example, crude, is fed to a fractional distillation column (ADU) and the material that is boiling at a temperature higher than 218 C (the boiling point for naphthalene) is fed to a series (or cascade) of hydrocracking process reactors with a range of operating conditions (increasingly stringent) / catalysts, etc. chosen to maximize the yield of suitable material for the production of aromatic compounds of LPG and ^b T ^x by means of hydrocracking processes, such as feed hydrocracking processes (FHC) or gasoline hydrocracking (GHC). After each step of hydrocracking, the remaining heavy material (boiling point> 218 C) is separated from the lighter products and only the heavier materials are fed to the next, more rigorous, hydrocracking phase, while the more light is separated and therefore is not exposed to additional hydrocracking. This lighter material (boiling point <218 C) is fed to a process of FHC or GHC for the production of aromatic compounds of LPG and BTX. The LPG products of the GHC / FHC unit can then be converted to light olefins using steam cracking and dehydrogenation processes or a combination of these processes. The present invention will be discussed in more detail in the experimental section of this application. The term "gasoline hydrocracking unit" or "GHC reactor" will be discussed later in this document. The term "feed hydrocracking unit" or "FHC reactor" will also be discussed later.

The present inventors optimize each step of the hydrocracking cascade (by means of the chosen operating conditions, the type of catalyst and the design of the reactor) so that the ultimate performance of desired products is maximized (hydrocarbon material with higher boiling point). that of methane and less than that of naphthalene) and the associated capital and operating costs are minimized.

The term "cascade of hydrocracking units" as used herein means a series of hydrocracking units. The hydrocracking units are separated from each other by a separation unit, that is to say a unit in which the cracked raw material is separated into an upper stream comprising a fraction of hydrocarbons of low boiling point and a lower stream comprising a heavy hydrocarbon fraction. And the lower stream comprising a heavy hydrocarbon fraction of a hydrocracking unit of this type is a raw material for a subsequent hydrocracking unit. A construction of this type is different from a construction in which several catalyst beds are arranged vertically, cascading the effluent from one bed into another bed, specifically from the upper bed to the lower bed, since such a cascade the intermediate stage of removal of the complete effluent and the separation thereof in an upper stream comprising a fraction of hydrocarbons of low boiling point and a lower stream comprising a heavy hydrocarbon fraction, the lower stream comprising a fraction of heavy hydrocarbons a raw material for a subsequent hydrocracking unit. The separation unit in the present document may comprise several separation sections.

According to a preferred embodiment of the present process, the lower boiling hydrocarbon products of all the hydrocracking units are hydrocarbons having a boiling point higher than that of methane and less than that of naphthalene.

According to the present process, each hydrocracking unit in the cascade of hydrocracking units is operated under liquid phase hydrocracking conditions, and the hydrocracking unit is operated as said BTX and LPG production unit under hydrocracking conditions in the gas phase. . In fact, the cascade of hydrocracking units operating under hydrocracking conditions in the liquid phase is placed in series, while the hydrocracking unit, that is, the BTX and LPG production unit, which operates in Gaseous phase hydrocracking conditions are placed in parallel with respect to the cascade of hydrocracking units operating under liquid phase hydrocracking conditions.

It is preferred to combine the lower boiling hydrocarbon fractions of all the hydrocracking units and process this combined stream as raw material for said BTX and LPG production unit, said unit preferably being a hydrocracking unit, the process conditions being that prevail in said production unit of BTX and LPG, that is to say gas phase hydrocracking conditions, different from the process conditions that prevail in any one of the cascade of hydrocracking units, that is to say liquid phase hydrocracking conditions.

In another embodiment it is preferred to send the lower boiling hydrocarbon products of all the hydrocracking units first to a separation section, separation section in which a fraction comprising C5- material is separated from the lower hydrocarbon products. boiling point, and the remaining part of the lower boiling hydrocarbon products is processed as raw material for said BTX and LPG production unit. Further, it is preferred to additionally process said C5- material in dehydrogenation units, preferably by previously pre-separating said C5- material in a stream comprising C3 and a stream comprising C4 and feeding said streams to a propane dehydrogenation unit and a butane dehydrogenation unit, respectively.

According to one embodiment it is preferred to separate the lighter part of this stream, ie the lower boiling hydrocarbon products from all the hydrocracking units, and only process the heavier part through GHC / FHC. This is because the GHC / FHC is intended to convert BTX joint boiling non-aromatic species (eg, paraffins and olefins) into LPG species, which can be separated and used as feeds for other petrochemical plants (eg dehydrogenation), and pure BTX aromatics. If there are already lPg species in the lower-boiling hydrocarbon products of the hydrocracking units, there is no need to process them through the GHC / FHC unit and no other reasons (for example, the need for a larger unit). ).

The exact cutoff point for the current to go to the GHC / FHC is somewhat flexible since this unit will deal with the LPG in the feed and it may still be useful to include C5 species in the feed for the GHC / FHC so that they can become Ethane, propane and butane, which can be used as feeds for the dehydrogenation units. For this reason it is preferred to include a separator (which uses conventional technology, such as distillation) in the feed for the GHC / FHC.

In one embodiment of this type there are three sensitive alternative cutting points for the lower boiling point hydrocarbon products. The first preferred embodiment is to process the full current by means of GHC / FHC without any separation-sensitive if only a small amount of LPG already exists as this will reduce the number of processing units (and therefore costs) without greatly increasing the size, etc. of the GHC / FHC.

The second preferred embodiment relates to the separation of the lower boiling hydrocarbon products into a C5- part and a C6 + part and processing the C6 + part via GHC / FHC to produce pure BTX and converting any non-aromatic compound C6 + into species of lPg. In parallel, process part C5- by means of some other unit (not specified) for which this is a good feed.

The third preferred embodiment refers to the separation of the lower boiling hydrocarbon products into a C4- (LPG) part and a C5 + part and processing the C5 + part by means of GHC / FHC to produce pure BTX and convert any non-active compound. C5 + aromatic in LPG species. In parallel, process part C4- (potentially in combination with the LPG product of the GHC / FHC) by means of some other unit, potentially after further separation into C2, C3 and C4 species, such as ethane steam crackers and dehydrogenation units of propane-butanes.

The present process further comprises separating hydrogen from the lower boiling hydrocarbon products and feeding the hydrogen thus separated to a hydrocracking unit in the cascade of hydrocracking units, the hydrogen thus being preferably fed separately to a previous hydrocracker unit in the cascade of hydrocracking units.

In another embodiment it is also preferred to feed the hydrogen thus separated to the production unit of BTX and LPG.

The hydrocarbon feedstock can be a cutoff from an atmospheric distillation unit (ADU) of crude oil, such as a lower stream or atmospheric gas oils, refinery process products, such as light cycle oil from a FCC unit or heavy cracked naphthas .

The present process further comprises further processing a fraction comprising LPG as produced in said LPG production unit as a raw material for one or more process units chosen from the group of steam cracking unit, aromatization unit, dehydrogenation unit of propane, butane dehydrogenation unit and mixed propane-butane dehydrogenation unit.

In specific embodiments may also be mentioned alkylation processes, high intensity catalytic cracking (including high intensity FCC), light naphtha (LNA) aromatization, reforming and mild hydrocracking. The choice of the petrochemical processes mentioned above depends, among others, on the composition of the low-boiling hydrocarbon fractions. If, for example, a stream comprising mainly C5 is obtained, the pentane dehydrogenation unit will be preferred. In addition, a stream of this type comprising mainly C5 can be sent to high intensity catalytic cracking (including high intensity FCC) to also produce propylene and ethylene. If, for example, a stream comprising mainly C6 is obtained, a process such as light naphtha (LNA) aromatization, reforming and mild hydrocracking will be preferred.

The present cascade of hydrocracking units comprises at least two hydrocracking units, said hydrocracking units preferably being preceded by a hydrotreating unit, the lower stream of said hydrotreating unit being used as raw material for said first hydrocracking unit, especially that in that the temperature prevailing in said hydrotreating unit is higher than in said first hydrocracking unit.

The temperature in the first hydrocracking unit is lower than the temperature in the second hydrocracking unit.

In addition, it is also preferred that the particle size of the catalyst present in the cascade of hydrocracking units decrease from the first hydrocracking unit to the subsequent hydrocracking units. According to the invention, the temperature in the cascade of hydrocracking units increases, the temperature prevailing in said second hydrocracking unit being higher than in said hydrotreating unit.

The reactor type design of the present hydrocracking units is chosen from the group of fixed bed type, the type of ebullient bed reactor and the type of suspension phase. This may involve a series of different processes such as first a fixed bed hydrotreater, followed by a fixed bed hydrocracker, followed by an ebullient bed hydrocracker, optionally followed by a hydrocracker in suspension. Therefore, the reactor type design of said hydrotreating unit is of the fixed bed type, the reactor type design of said first hydrocracking unit can be the type of fixed bed or ebullient bed reactor and the design of The reactor type of said second hydrocracking unit can be the ebullient bed reactor or the suspension phase type.

In the present process it is preferred to recirculate the lower stream of the final hydrocracking unit to the inlet of said final hydrocracking unit.

The process conditions that prevail in the production unit of BTX and LPG are different from the process conditions that prevail in any one of the cascade of hydrocracking units.

The use of hydrocarbons having a boiling point lower than that of naphthalene and produced in a cascade of hydrocracking units as raw material for a BTX and LPG production unit comprises, in particular, the recovery of hydrogen from the effluent (s) of said production unit of BTX and LPG and recirculate said hydrogen thus recovered at the entrance of said production unit of BTX and LPG.

Therefore, the present process preferably comprises feeding the stream comprising C5 + to a second hydrocracking unit. An additional advantage is the possibility of integrating the previous heating of the C5 + feed for the second hydrocracking unit that comes from the first hydrocracking unit with the hot effluent.

As used herein, the term "gasoline hydrocracking unit" or "GHC" refers to a unit for performing a hydrocracking process suitable for converting a complex hydrocarbon feed that is relatively rich in aromatic hydrocarbon compounds - such as light distillate derived from a refinery unit including, but not limited to, reformer gasoline, FCC gasoline and pyrolysis gasoline - in LPG and BTX, the process being optimized to maintain an intact aromatic ring of the aromatic compounds included in the GHC feed stream, but remove most of the side chains from the aromatic ring. Therefore, the main product produced by gasoline hydrocracking is BTX and the process can be optimized to provide ^b T ^x of quality as a chemical product. Preferably, the hydrocarbon feed that is subjected to gasoline hydrocracking comprises light distillate derived from a refinery unit. More preferably, the hydrocarbon feed that is subjected to gasoline hydrocracking preferably does not comprise more than 1% by weight of hydrocarbons having more than an aromatic ring. Preferably, gasoline hydrocracking conditions include a temperature of 300-580 ° C, more preferably 450-580 ° C and even more preferably 470-550 ° C. Minor temperatures have to be avoided, since the hydrogenation of the aromatic ring becomes favorable. However, in the event that the catalyst comprises an additional element that reduces the hydrogenation activity of the catalyst, such as tin, lead or bismuth, lower temperatures can be selected for gasoline hydrocracking; see, for example, WO 02/44306 A1 and WO 2007/055488. In the event that the reaction temperature is too high, the performance of the LPG (especially propane and butanes) decreases and the methane yield increases. As the activity of the catalyst can decrease over the lifetime of the catalyst, it is advantageous to increase the reactor temperature gradually over the lifetime of the catalyst to maintain the hydrocracking conversion rate. This means that the optimum temperature at the start of an operating cycle is preferably at the lower end of the hydrocracking temperature range. The optimum reactor temperature will increase as the catalyst is deactivated, so that at the end of a cycle (shortly before the catalyst is replaced or regenerated), the temperature is preferably selected at the upper end of the temperature range of hydrocracking

Preferably, the gasoline hydrocracking of a hydrocarbon feed stream is carried out at a pressure of 0.3-5 MPa gauge, more preferably at a pressure of 0.6-3 MPa gauge, particularly preferably at a pressure of 1- 2 MPa gauge and most preferably at a pressure of 1.2 1.6 MPa gauge. By increasing the reactor pressure, the conversion of non-aromatic C5 + compounds can be increased, but this also increases the methane yield and the hydrogenation of aromatic rings to give cyclohexane species that can be cracked to give LPG species. This results in a reduction of the aromatic yield as the pressure is increased and, as part of the cyclohexane and its methylcyclopentane isomer, are not completely hydrocracked, there is an optimum in the purity of the resulting benzene at a pressure of 1.2-1. , 6 MPa.

Preferably, gasoline hydrocracking of a hydrocarbon feed stream is performed at a weight hourly space velocity (WHSV ) of 0.1-20 h -1, more preferably at a weight hourly space velocity of 0. , 2-10 h-1 and most preferably at a weight hourly space velocity of 0.4-5 h-1. When the space velocity is too high, not all of the paraffin components that boil with BTX are hydrocracked, so that it will not be possible to achieve the BTX specification by simple distillation of the reactor product. At too low a space velocity, the methane yield increases at the expense of propane and butane. By selecting the optimum hourly weight space velocity, it was surprisingly found that a sufficiently complete reaction of the co-boiling compounds is achieved to produce BTX in specification without the need for liquid recirculation.

Accordingly, the preferred gasoline hydrocracking conditions therefore include a temperature of 450-580 ° C, a pressure of 0.3-5 MPa gauge and a weight hourly space velocity of 0.1-20 h -1. More preferred gasoline hydrocracking conditions include a temperature of 470-550 ° C, a pressure of 0.6-3 MPa gauge and a weight hourly space velocity of 0.2-10 h-1. Particularly preferred petrol hydrocracking conditions include a temperature of 470-550 ° C, a pressure of 1-2 MPa gauge and a weight hourly space velocity of 0.4-5 h -1.

As used herein, the term "feed hydrocracking unit" or "FHC" refers to a unit for performing a suitable hydrocracking process to convert a complex hydrocarbon feed that is relatively rich in naphthenic and paraffinic hydrocarbon compounds - such as first distillation cuts that include, but are not limited to, naphtha - in LPG and alkanes. Preferably, the hydrocarbon feed that is subjected to feed hydrocracking comprises naphtha. Accordingly, the main product produced by feed hydrocracking is LPG which must be converted to olefins (ie it must be used as feed for the conversion of alkanes to olefins). The FHC process can be optimized to maintain an intact aromatic ring of the aromatic compounds comprised in the FHC feed stream, but remove most of the side chains of the aromatic ring. In such a case, the process conditions to be employed for FHC are comparable to the process conditions that must be used in the g Hc process as described earlier in this document. Alternatively, the FHC process can be optimized to open the aromatic ring of the aromatic hydrocarbons included in the FHC feed stream. This can be achieved by modifying the GHC process as described herein by increasing the hydrogenation activity of the catalyst, optionally in combination with the selection of a lower process temperature, optionally in combination with a reduced space velocity. In such a case, the preferred feed hydrocracking conditions thus include a temperature of 300-550 ° C, a pressure of 300-5000 kPa gauge and a weight hourly space velocity of 0.1-20 h -1. More preferred hydrocracking feed conditions include a temperature of 300-450 ° C, a pressure of 300-5000 kPa gauge and a weight hourly space velocity of 0.1-10 h -1. Even more preferred FHC conditions optimized for ring opening of aromatic hydrocarbons include a temperature of 300-400 ° C, a pressure of 600-3000 kPa gauge and a weight hourly space velocity of 0.2-5 h -1.

As used herein, the term "C # hydrocarbons" or "C #", where "#" is a positive integer, is intended to describe all hydrocarbons that have # carbon atoms. In addition, the term "C # +" or "C # +" hydrocarbons is intended to describe all hydrocarbon molecules that have # or more carbon atoms. Accordingly, the term "C5 + hydrocarbons" or "C5 +" is intended to describe a mixture of hydrocarbons having 5 or more carbon atoms. Accordingly, the term "C5 + alkanes" refers to alkanes having 5 or more carbon atoms. Accordingly, the term "C # less hydrocarbons" or "C # less" is intended to describe a mixture of hydrocarbons having # or less carbon atoms and including hydrogen. For example, the term "C2-" or "C2 minus" refers to a mixture of ethane, ethylene, acetylene, methane and hydrogen. Finally, the term "C4 mixture" is intended to describe a mixture of butanes, butenes and butadiene, ie n-butane, i-butane, 1-butene, cis- and trans-2-butene, i-butene and butadiene.

The term "olefin" is used herein having its meaning widely established. Accordingly, olefin refers to an unsaturated hydrocarbon compound containing at least one carbon-carbon double bond. Preferably, the term "olefins" refers to a mixture comprising two or more of ethylene, propylene, butadiene, butylene-1, isobutylene, isoprene and cyclopentadiene.

The term "LPG" as used herein refers to the widely-established acronym for the term "liquefied petroleum gas". The LPG generally consists of a mixture of C3-C4 hydrocarbons, ie a mixture of C3 and C4 hydrocarbons.

One of the petrochemical products produced in the process of the present invention is BTX. The term "BTX" as used herein refers to a mixture of benzene, toluene and xylenes. Preferably, the product produced in the process of the present invention comprises additional useful aromatic hydrocarbons, such as ethylbenzene. Accordingly, the present invention preferably provides a process for producing a mixture of benzene, toluene, xylenes and ethylbenzene ("bTx E"). The product as produced may be a physical mixture of the different aromatic hydrocarbons or may be directly subjected to further separation, for example by distillation, to provide different purified product streams. Such a purified product stream may include a benzene product stream, a product stream of toluene, a product stream of xylene and / or a product stream of ethylbenzene.

The invention will now be described in more detail and together with the accompanying drawings, in which the same elements or similar elements are designated with the same number.

Figure 1 is a schematic illustration of an embodiment of the process of the invention.

Figure 2 is a schematic illustration of another embodiment of the process of the invention.

Referring now to the process and apparatus 1 depicted schematically in Figure 1, there is shown a feed of crude 1, an atmospheric distillation unit 2 for separating the crude in stream 29, which comprises hydrocarbons having a lower boiling point than that of naphthalene. The lower stream 3 leaving the distillation unit 2 is fed to a hydroprocessing unit 4, for example, a hydrotreating unit, in which the hydrocarbons 5 thus treated are sent to a separation unit 6 producing a gaseous stream 7 and a lower stream 13 comprising hydrocarbons having a boiling point of naphthalene and higher. The stream 7 is further separated in the separation unit 8 in a stream 9 comprising hydrogen and a lower stream 12 comprising hydrocarbons having a boiling point lower than that of the naphthalene. The stream 13 is fed to a hydrocracking unit 15 and its effluent 16 is sent to a separation unit 17 which produces a gaseous stream 18 and a lower stream 20 comprising hydrocarbons having a boiling point of naphthalene and above. The stream 18 is further separated in a separation unit 19 in a stream 14, which comprises hydrogen, and a stream 21, which comprises hydrocarbons having a boiling point lower than that of the naphthalene. The accumulation of hydrogen is indicated by the reference number 10. The effluent 20 from the separation unit 17 is sent to an additional hydrocracking unit 22 and its effluent 23 is sent to a separation unit 24 which produces an upper stream 44 and a lower stream 27. The upper stream 44 is further separated in a separation unit 38 in a stream 26 comprising hydrogen and a lower stream 28 comprising hydrocarbons having a boiling point lower than that of naphthalene. The hydrogen-containing stream leaving the separation unit 38 sends a compressor 11 and is returned to the inlet of the hydrocracking unit 22. The same recirculation is applicable for the streams 9, 14. The upper stream coming from the unit of distillation 2 and currents 12, 21 and 28 are combined as a stream 29, stream 29 which is sent directly to a hydrocracker 30. The processing of the complete stream 29 by means of the unit 30 without any separation is sensitive if it only exists and a small amount of LPG in stream 29, since this will reduce the number of processing units (and therefore costs) without greatly increasing the size, etc. of the hydrocracker unit 30.

According to a preferred embodiment, it is also possible to separate the stream 29 in a separation unit 60 into a part C5- (stream 61) and a part C6 + (stream 62), and process the part C6 + by means of a unit 30 for produce pure BTX and convert any non-aromatic compound C6 + into LPG species. In parallel, process part C5- by means of some other unit (not specified) for which this is a good feed.

According to another preferred embodiment, it is also possible to separate the stream 29 in a part C4- (LPG) (stream 61), and a part C5 + (stream 62), and process the part C5 + (stream 62), by means of a unit 30. to prepare pure BTX and convert any non-aromatic compound C5 + into LPG species. In parallel, process part C4- (stream 61, potentially in combination with the LPG product of unit 30, ie stream 36, by means of some other unit, for example, propane / butane dehydrogenation units.

The effluent 31 of the hydrocracking unit 30 is sent to a separation unit 32 which produces an upper current 33 and a lower current 35, comprising mainly BTX. The upper stream 33 is further separated in a separation unit 34 in a stream 36, which comprises LPG, and an upper stream 37, which comprises hydrogen. Stream 37 is recirculated to the inlet of hydrocracking unit 30.

According to FIG. 2, the process and the apparatus are identified with the reference number 2, in which crude 1 is sent to a distillation unit 2 and is separated into an upper stream 29 and a lower stream 3. The lower stream 3 it is sent to a hydrocracking unit 4, especially a hydrotreating unit, which produces an effluent 5. The effluent 5 is sent to a separation unit 6 which produces an upper stream 7 and a lower stream 13, which comprises hydrocarbons having a boiling point of naphthalene and higher. The upper stream 7 is further separated into separation unit 8 in an upper stream 40, which comprises mainly hydrogen, and a lower stream 12, which comprises hydrocarbons having a boiling point lower than that of naphthalene. The stream 13 is sent to a first hydrocracking unit 15 which produces an effluent stream 16. The effluent stream 16 is sent to a separation unit 17 which produces an upper stream 18 and a lower stream 20. The stream 18 is separated additionally in a separation unit 19 producing a stream 43, comprising hydrogen. The stream 43 is recirculated in Figure 2 to the inlet of the hydrocracking unit 4. The lower stream 21 of the separation unit 19 is combined with the upper stream 29 of the unit 2 and sent to the hydrocracking unit 30.

The processing of the full current 29 by means of the unit 30 without any separation is sensitive if only a small amount of LPG already exists in the stream 29, since this will reduce the number of processing units (and therefore the costs) without greatly increase the size, etc. of the hydrocracker unit 30.

According to a preferred embodiment, it is also possible to separate the stream 29, before entering the unit 30, into a part C5- (stream 61), and a part C6 + (stream 62), and process the part C6 + (stream 62), by means of unit 30 to produce pure BTX and convert any non-aromatic compound C6 + into LPG species. In parallel, process part C5- (stream 61) by means of some other unit (not specified) for which this is a good feed.

According to another preferred embodiment, it is also possible to separate the stream 29, before entering the unit 30, into a part C4- (stream 61) (LPG) and a part C5 + (stream 62) and process the part C5 + (stream 62) by means of unit 30 to produce pure BTX and convert any non-aromatic compound C5 + into LPG species. In parallel, process part C4- (stream 62, potentially in combination with the LPG product of unit 30, ie stream 36) by means of some other unit, for example (propane / butane dehydrogenation units).

The lower stream 20 of the separation unit 17 is sent to a second hydrocracking unit 22 which produces an effluent 23. The effluent 23 is further separated in a separation column 24 in an upper stream 45 and a lower stream 27, qualified as heavy pitch. A part of the stream 27 is recirculated as stream 25 to the inlet of the second hydrocracking unit 22. In the separation column 38, the overhead stream 45 is further separated into an overhead stream 42, comprising mainly hydrogen, and a stream lower 28, which mainly comprises hydrocarbons having a boiling point lower than the boiling point of naphthalene. The hydrogen-containing stream 42 is recirculated at the inlet of the hydrocracking unit 15. The overhead stream 40 leaving the separation column 8 combines with the hydrogen accumulation 10 and forms a stream 41 as the inlet stream for the hydrocracking 30. The effluent 31 coming from the hydrocracking unit 30 is further separated in a separation unit 32 in an upper stream 33 and a lower stream 35, comprising BTX. The upper stream 33 is further separated in a separation column 34 in a stream 36, which mainly comprises LPG.

According to another embodiment, it is preferred to redesign units 30, 32 and 33 to convert the aromatic and naphthenic species into stream 29 (which includes the material of streams 12, 21 and 28) into LPG. This embodiment can be identified as an "indirect" route since each hydrocracker unit in the cascade produces some LPG material, but also other species that become LPG in a second hydrocracker. This will mean an operation of the hydrocracking unit 30 at a lower temperature and a higher hydrogen partial pressure. There is a change in the distillation section of this installation, since you can either delete column 32 (since there is no product stream from BTX 35) or use column 32 as a way to recirculate more material heavy than the LPG (stream 35) back to the reactor (unit 30). In this manner of operation, the reactors and the separation systems for the other hydrocrackers can continue to be operated as described above.

Claims (12)

1. - A process for converting a high-boiling hydrocarbon feedstock into lower-boiling hydrocarbon products, said boiling-point hydrocarbon products being suitable as feedstock for petrochemical processes, said conversion process comprising the following steps of: feeding a heavy hydrocarbon first material to a cascade of hydrocracking units, the cascade of hydrocracking units comprising at least two hydrocracking units, cracking said raw material in a hydrocracking unit, separating said cracked raw material into an upper stream comprising a fraction of low boiling hydrocarbons and a lower stream comprising a heavy hydrocarbon fraction feeding said lower stream of a hydrocracking unit of this type as raw material for a subsequent hydrocracking unit in said cascade of hydrocracking units, the process conditions being in each of the hydrocracking units different from each other, wherein the temperature from the first to the subsequent hydrocracking units increases, and process the lower boiling hydrocarbon fractions of each of the hydrocracking units as raw material for a BTX and LPG production unit, said bTx and LPG production unit being a hydrocracking unit, the process conditions being that prevail in said hydrocracking unit different from the process conditions prevailing in any one of the hydrocracking units in the cascade of hydrocracking units, each hydrocracking unit being operated in said cascade of hydrocracking units under conditions of phase hydrocracking liquid, and said hydrocracking unit being operated as said production unit of BTX and LPG under hydrocracking conditions in the gas phase. 2. The process according to claim 1, wherein the hydrocarbon fractions of lower boiling point of all the hydrocracking units in said cascade of hydrocracking units are hydrocarbons having a boiling point lower than that of naphthalene. units 3. The process according to any one or more of claims 1-2, wherein the hydrocarbon fractions of lower boiling point of said hydrocracking units are sent to a separation section, section in which a fraction comprising material C5- is separated from said fractions of lower boiling hydrocarbons, and the remaining part of said lower boiling hydrocarbon fractions is processed as a raw material for said production unit of BTX and LPG. 4. - The process according to claim 3, further comprising processing said C5- material into dehydrogenation units, preferably further pre-separating said C5-material in a stream comprising C3 and a stream comprising C4 and feeding said streams to a propane dehydrogenation unit and a butane dehydrogenation unit, respectively. 5. - The process according to any one or more of the preceding claims, which further comprises separating the hydrogen from said hydrocarbon fractions of lower boiling point and feeding said hydrogen thus separated to a hydrocracking unit in said cascade of hydrocracking units, especially which further comprises feeding said hydrogen thus separated to a previous hydrocracker unit in said cascade of hydrocracking units, especially which further comprises feeding said hydrogen thus separated to said production unit of BTX and LPG. 6. - The process according to any one or more of the preceding claims, wherein said heavy hydrocarbon prime material is selected from the crude atmospheric distillation unit (ADU) group, such as lower stream, atmospheric gas oils and process products. refinery, such as light cycle oil from a FCC unit or heavy cracked naphthas. 7. - The process according to any one or more of the preceding claims, further comprising processing a fraction comprising LPG as produced in said LPG production unit as a raw material for one or more process units chosen from the unit group steam cracking, aromatization unit, propane dehydrogenation unit, butane dehydrogenation unit and mixed propanobutane dehydrogenation unit. 8. - The process according to any one or more of the preceding claims, wherein said hydrocracking units are preferably preceded by a hydrotreating unit, in which the lower stream of said hydrotreating unit is used as a raw material for said first hydrotreating unit. hydrocracking unit, especially that the temperature prevailing in said hydrotreating unit is higher than in said first hydrocracking unit. 9. - The process according to any one of claims 1-8, wherein the temperature in the first hydrocracking unit is lower than the temperature in the second hydrocracking unit, especially in which the particle size of the catalyst present in the cascade of hydrocracking units decreases from the first hydrocracking unit to the subsequent hydrocracking units. 10. - The process according to any one of claims 8-9, wherein the temperature in the cascade of hydrocracking units increases, wherein the temperature prevailing in said second hydrocracking unit is higher than in said hydrotreating unit. . 11. - The process according to any one or more of the preceding claims, wherein the reactor type design of the hydrocracking units is chosen from the group of the fixed bed type, the type of ebullient bed reactor and the type of suspension phase, the reactor type design of said hydrotreating unit preferably being of the fixed bed type, the reactor type design of said first hydrocracking unit preferably being of the ebullient bed reactor type, the type design being of reactor of said second hydrocracking unit preferably of the suspension phase type. 12. - The process according to any one or more of the preceding claims, wherein the lower stream of the final hydrocracking unit is recirculated to the inlet of said final hydrocracking unit.